Steroids are not dangerous just because they are labeled "steroids" - that covers a whole range of medications. I have been given steroids (prednisone) for asthma attacks that got bad enough to be hospitalized. Yes, there were side effects - I got pink cheeks, and felt incredibly hungry, but it knocked back the inflammation and I was able to breathe again. And once the crisis was past, I gradually "stepped down" and the side effects went away.

This may be similar to what they want to do for your kitty. I know some people end up on low-dose prednisone long term, but breathing IS important!